Hard Disk Drives Overview

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Questions and Answers

What is a head crash in relation to hard disk drives?

A failure caused by the read-write head contacting the platter (correct)

A malfunction that occurs when the drive overheats

An issue primarily caused by software installation errors

A temporary loss of data due to software malfunction

Which aspect of hard drive performance is NOT monitored by SMART?

Internal temperature

Power on hours

Seek error count

Data compression ratio (correct)

Why is it essential to monitor SMART data on hard drives?

It minimizes the electrical consumption of the drive

It helps increase the disk storage capacity

It improves the speed of data retrieval

It provides early warning of potential drive failures (correct)

Which situation can initiate a head crash?

Excessive shock or vibration Signup and view all the answers

What type of software is needed to collect and display SMART data?

Freeware/shareware SMART interface programs Signup and view all the answers

What is the purpose of rotational delay in hard drive performance?

It is the time taken for the desired sector to be ready for reading. Signup and view all the answers

How is access time calculated for hard drives?

It is seek time plus rotational delay. Signup and view all the answers

Which component ensures that the BIOS can properly access a hard drive?

The hard drive geometry. Signup and view all the answers

What limitation did the 28-bit addressing method impose on older computers?

It limited hard drive storage capacity to 137 GB. Signup and view all the answers

What does LBA stand for in the context of hard drive addressing?

Logical Block Addressing. Signup and view all the answers

Which of the following best describes write precompensation on hard drives?

It involves increasing sensitivity to read smaller sectors. Signup and view all the answers

What is a common issue with hard drive capacity advertising by manufacturers?

They report total capacity without formatting considerations. Signup and view all the answers

What type of hard drive interface uses a 7 pin data connector?

SATA. Signup and view all the answers

Which component of a hard drive is responsible for storing data on magnetic surfaces?

Read/write heads Signup and view all the answers

What is the purpose of the barometric filter in a hard drive?

To enable pressure equalization Signup and view all the answers

Which of the following is the smallest unit of space on a hard drive that can be allocated?

Sector Signup and view all the answers

How has the data transfer rate of hard drives evolved from its early days?

Increased from 85KBps to 150MBps Signup and view all the answers

What risk is associated with a hard disk drive being assembled in a clean room?

Accumulation of dust particles Signup and view all the answers

What is defined as a group of tracks of the same diameter within a hard drive?

Cylinder Signup and view all the answers

What is one important care instruction for maintaining a hard disk drive?

Avoid exposing it to extreme temperatures Signup and view all the answers

Which type of motor is used in modern hard drives to move the read/write heads?

Voice coil motor Signup and view all the answers

What is the rotation speed of most modern hard drives?

5,400 rpm or 7,200 rpm Signup and view all the answers

What typically happens to malfunctioning hard drives?

They are usually replaced Signup and view all the answers

How has the storage capacity of hard drives changed over time?

Increased from 5MB to over 8TB Signup and view all the answers

What does seek time measure in a hard disk drive?

The time required to move the disk arm to a desired cylinder Signup and view all the answers

Which components make up the internal assembly of a hard drive?

Platters and read/write heads Signup and view all the answers

What can clusters range from in terms of sectors, depending on drive formatting?

2 to 64 Signup and view all the answers

Which of these materials are platters typically made from?

Aluminum or ceramic composite Signup and view all the answers

Study Notes

Hard Disk Drives

Hard disk drives (HDDs) are the primary storage devices in most modern computers.
HDDs store data for the computer system, including applications and operating systems.
Early HDDs were slow and unreliable, but advancements have made them much faster and more reliable.

Hard Drive Advancements

Storage capacity: Originally 5MB, now up to 8TB+.
Data transfer rates: Originally 85KBps, now 150MBps+.
Access time: Originally around 85ms, now 10-20ms.
Cost: Originally $2,000 for 10MB, now well under $100 for 1TB.

Inside a Hard Drive

Components: Platters, read/write heads, actuator arms, motors, air filters.
Platters: Made from aluminum or ceramic composite material; rugged and solid; store data. They are lightweight and have low thermal expansion.
Air Filters: Recirculating filter, and barometric filter. The recirculating filter filters small particles while the barometric filter provides ventilation for pressure equalization.

Care of a Hard Disk Drive

Extreme temperatures: Avoid exposing HDDs to extreme temperatures, such as those found in a car trunk.
Safe operating temperatures: If exposed to extreme temperatures, wait until the HDD reaches safe operational temperature before powering it on.

Read/Write Heads

Coated platters: Both sides of the platter are coated with magnetic surfaces for data storage.
Two heads: Each platter needs two read/write heads, one for each side.
Air cushion: The heads float on a thin air cushion, never making contact with the platter surface during operation.
Extremely small air buffer: The air buffer space between the read/write head and the platter is very small, measured in millionths of inches.

Actuator Arm

Read/write head location: Read/write heads are located on the actuator arm's tip.
Voice coil motor: In modern HDDs, the actuator arm is positioned by a voice coil motor.

Spindle

Multiple platters: HDDs have multiple platters, separated by spacers and held together.
Rotation: The spindle and platters rotate at a constant speed.

Voice Coil Motor

Linear motor or voice coil: Current HDDs utilize this technology to move the actuator arm
Magnetic field: Electrical current generates a magnetic field that moves the actuator arm.
Improved performance: Significantly faster, more accurate, and more reliable than stepper motors.
Automatic parking: Hard drive heads automatically park when not in use.

Full Speed Ahead

RPM rates: Most HDDs spin at either 5,400 or 7,200 RPM.
High Performance: High-performance HDDs spin at 10,000 RPM or higher; some models up to 15,000 RPM.

Hard Drive Assembly

Clean rooms: HDDs are assembled in sealed clean rooms under sanitary conditions.
Dust sensitivity: A tiny speck of dust can cause a hard drive head crash.
Repair limitations: Few companies have the capacity for HDD repair due to complexity and expense.
Replacement: Malfunctioning HDDs are typically replaced.

Hard Drive Organization

Tracks: Concentric circles on the platter; thousands per platter.
Cylinders: Tracks of the same diameter on all platters are a cylinder.
Sectors: Sections of a track; smallest allocatable unit. Old HDDs typically held 512 bytes per sector; modern HDD uses 4KB.
Clusters: Groups of sectors; the smallest unit of space that can be used for a read/write operation.

Logical Block Addressing (LBA)

Modern method: Using logical block addressing (LBA), each sector on a HDD is assigned a unique identifier.
Older addressing: Older computers used 28-bit addressing which limited maximum storage to 137GB.
Modern addressing: Current systems use 48-bit addressing, allowing HDDs up to 144PB.

Hard Drive Interfaces

Interfaces: Three major interfaces exist: Serial ATA (SATA), Parallel ATA (PATA) and Small Computer System Interface (SCSI).
SATA: 7 pin data connector
PATA: 40 pin data connector
SCSI: Variety of connectors; typically used in servers

Capacity Confusion

GB calculation: Some HDD manufacturers calculate capacity in gigabytes by dividing by 1000 (rather than 1024).
Advertised vs. formatted: This results in an advertised capacity that's noticeably higher than the operating system's reported capacity.

Head Crash

Contact damage: A head crash occurs when a read/write head touches a rotating platter.
Data loss: This results in permanent damage to the magnetic media on the hard drive's platter, leading to data loss.
Causes: A head crash can occur due to dirt, or too much shock or vibration.

SMART

Self-Monitoring Analysis and Reporting Technology (SMART): An interface for monitoring hard drive performance and condition.
Predictive maintenance: SMART allows for the predictive maintenance.
Data backup: Vital information can alert users to impending failure, allowing ample time to back up data.
Diagnostics: Provides information on aspects of the internal operation of a hard drive such as internal temperature, Power-on hours, spin-up retry count, Power cycle count, Seek error count, and Throughput performance.
Software required: Software is required to collect and display SMART data. Freeware/Shareware software solutions are available, alongside commercially available programs.

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Description

This quiz delves into hard disk drives, exploring their historical evolution, advancements in storage capacity, data transfer rates, and access times. Additionally, it covers the various components that make up a hard drive, providing a comprehensive understanding of its functionality and importance in modern computing.